Power plants gear up for summer of heat and potential...

1of 24Robert Harris, plant manager, walks through NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

2of 24Robert Harris, plant manager, walks through NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

3of 24The main power transformer is shown at the NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

4of 24NRG's TH Wharton Generating Station is shown on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

5of 24A door panel is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

6of 24Keith Sanderson, operations manager, walks past the No. 3 steam turbine at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

7of 24A heat recovery steam generator is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

8of 24A heat recovery steam generator is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

9of 24J.C. Cleburne works in the control room at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

10of 24J.C. Cleburne, left, and William Holloway work in the control room at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

11of 24A panel in the control room is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

12of 24A simple cycle gas turbine with cooling towers are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

13of 24Cooling towers are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

14of 24Cooling towers are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

15of 24A warning sign is shown on a steam drain pipe at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

16of 24Generator filters are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

17of 24An exhaust duct door is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

18of 24Piping is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

19of 24Cooling towers are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

20of 24Bypass dampers are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

21of 24Generator filters are shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

22of 24Robert Harris, plant manager, checks on the turbine controls at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

23of 24A 900 horsepower cranking motor is shown at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

24of 24A worker checks on one of the systems under maintenance at NRG's TH Wharton Generating Station on Tuesday, April 3, 2018, in Houston. NRG is preparing its Houston-area power plants for the summer as Texas is expected to shatter power demand records and the state's power reserves are the lowest they have been in nearly a decade. ( Brett Coomer / Houston Chronicle )Photo: Brett Coomer, Staff / Houston Chronicle

Texas power generators are preparing their plants for what could be a summer of extreme heat, power shortages and spiking market prices.

At NRG Energy’s TH Wharton natural gas plant in northwest Houston, workers have spent months rebuilding one of the plant’s 16 natural gas-fueled turbines and running checks on the 900 megawatt plant designed to respond rapidly to changing electricity consumption, firing when when demand and prices are high, and coming offline when they wane. All summer preparation has to be done by May 1, before Texas’ scorching summer kicks into gear.

“My job is to be ready to go when called upon,” said Robert Harris, the plant’s manager.

Harris’ day at Wharton starts at 6:30 a.m., prioritizing a list of fixes on the plant, which dates from the 1970s but has been updated over the decades.

Maintenance to prepare the plant for summer is a yearly event, but this year the stakes are higher. Following the shut down of three coal-fired power plants earlier this year, Texas’ power reserves to meet summer demand peaks is the lowest in a decade. The state is expected to see record-breaking power demand, according to the Electric Reliability Council of Texas, which oversees 90 percent of the grid. If a plant unexpectedly shuts down, it could upset the flow of power on grid, triggering calls for power conservation or, at the worst, planned rolling outages.

The summer is also a crucial time for merchant power companies like NRG, which rely on summer demand and pricing increases to make money. The combination of low power reserves and strong demand this summer is expected to drive up wholesale power prices, benefiting plants like TH Wharton that don’t run year round.

Wind power, which accounted for 20 percent of Texas’ energy mix last year, has changed how plants like Wharton operate. Before Texas became home to more than 20,000 megawatts of wind power — more than any other state — Wharton would run round the clock for days at a time. But now Wharton runs around 1,000 times a year, often for a few hours at a time, usually in the summer.

Ryan Maye Handy covers the regulation of utilities and oil and gas in Texas. She follows the Railroad Commission of Texas, the state’s oil and gas regulator, and the Public Utility Commission, and tracks trends in renewable energy growth across the state. She came to the Houston Chronicle in October 2016 from Colorado, where she worked as a reporter for nearly six years covering energy and the environment, county government and natural disaster recovery.